Certain optically active 3,4-dihydrobenzopyran-4-ols which are intermediates

Abstract

The (3S,4R)-isomer of a compound of formula (E) is disclosed. ##STR1##

What is claimed is: 
     
       1. The (3S,4R)-isomer of a compound of Formula (E) ##STR8## wherein the NH 2  and OH moieties are trans, and wherein one of R 1  ' and R 2  ' is hydrogen and the other is selected from the group consisting of C 1-6  alkylcarbonyl, C 1-6  alkoxycarbonyl, C 1-6  alkylcarbonyloxy, C 1-6  alkylhydroxymethyl, nitro, cyano, chloro, trifluoromethyl, C 1-6  alkylsulphinyl, C 1-6  alkylsulphonyl, C 1-6  alkoxysulphinyl, C 1-6  alkoxysulphonyl, C 1-6  alkylcarbonylamino, C 1-6  alkoxycarbonylamino or aminosulphinyl, aminosulphonyl or aminocarbonyl, the amino moiety being optionally substituted by one or two C 1-6  alkyl groups, or C 1-6  alkylsulphinylamino, C 1-6  alkylsulphonylamino, C 1-6  alkoxysulphinylamino or C 1-6  alkoxysulphonylamino or ethylenyl terminally substituted by C 1-6  alkylcarbonyl, nitro or cyano, or C 1-4  (alkyl)NOH or C 1-4  (alkyl)NNH 2 , one of R 3  and R 4  is hydrogen or alkyl having from 1 to 4 carbon atoms and the other is alkyl having from 1 to 4 carbon atoms, or R 3  and R 4  together are C 2-5  polymethylene; optionally in admixture with up to 40% of the corresponding (3S,4R)-isomer.   
     
     
       2. The (3S,4R)-isomer according to claim 1, optionally in admixture with 0 to 5% of the corresponding (3S,4R)-isomer. 
     
     
       3. A (3S,4R)-isomer according to claim 1, which is (+)-trans-4-amino-6-cyano-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-3-ol.